I like Elie Saab and R&R. So I'll be happy if one of those designers are making her wedding dress. I also like Marchesa (many of my fav gowns are from Marchesa) but because of the scandal, I doubt it would be choosen, pity. Versace and Prada have stunning gowns from time to time.
For other acessories, I would pick Michael Kors, I love Michael Kors shoes and watches (though I know many people would pick Christian Louboutin for shoes instead).
I hope she doesn't pick Chanel or Gucci. I know these are top brands and famous, but I don't know how celebrities like them so much. Chanel has so many horrid styles, and Gucci has terrible prints and patterns and sometimes over-the-top colours on their clothes. So please, don't...